Laser profiling projects a laser line onto the internal circumference of the pipe being inspected. This is viewed and the image captured by a CCTV camera. The resulting image can be measured to provide an accurate profile of the inside of the pipe. This shows any ovality, encrustation, loss of wall material due to corrosion, etc.
The laser profiler is usually used in conjunction with a CCTV inspection system that is crawler-mounted. These systems may be used in sewers, water mains, gas mains, culverts, rising mains etc. Normal practice is for the pipe to be empty, as for CCTV, although some systems will operate in gravity pipes that are partly full but Will provide data only for the area above the surface of the liquid.
Systems are available for use with crawler-mounted CCTV systems in the full range of diameters in which they operate, above and can be used over almost any length, this being dependant on the length and capacity of the umbilical cable
Limitations are that the pipeline should be as clean as possible to ensure the best view of the inner surface with obstructions removed when encountered.
Laser profiling enables engineers to view and measure the changes in diameter of the inner surface of a pipeline without the need for man-entry operations It can highlight defects and provide a permanent record of the state of the asset at the time of the survey, as a baseline against which to measure any future deterioration in subsequent surveys, thus adding to the data recorded by using CCTV alone.
The system can be used to determine the extent to which a pipeline has deformed and therefore the type of renovation or replacement technology that might be employed to provide a working solution to any problems occurring in the pipeline. Data and images from currently available systems can often be accessed via the internet or Wi-Fi from almost any location enabling survey data to be viewed almost immediately after a survey is completed. This enables immediate responses to be made if any pipeline shows such serious defects that such a response is necessary.
Since its introduction in the early 1970’s, Closed Circuit Television (CCTV) technology has made major advances in its technical capabilities. The addition of a Laser profiling system enables variations in the pipe profile to be determined.
Crawler-mounted CCTV camera systems are usually employed with Laser Profilers as the CCTV image of the projected laser line is what provides the basis on which to measure deformations recorded by the Laser system. During the course of a CCTV survey the laser projects a circular ring onto the inside of the pipeline wall. If the pipe is still circular (or any non-standard shape) the ring profile remains constant in the CCTV image. If the pipe shape changes the shape of the laser ring changes in accordance with the deformation encountered. Thus the change in ring shape indicates the change in the inner profile of the pipeline.
This knowledge is required if a renovation technique is to be employed, particularly where the renovation product is solid state and inflexible to provide the minimum dimensions of the pipe into which the renovation product must fit. For flexible pipes, such as GRP, PE and PVC, it also provides indication of potential incipient structural failure.
Specially designed software facilitates this recording (including images, defect assessment, distance along the survey and notation process) as well as offering immediate access to survey results to the client software.
Armed with this information the design engineer may then design the appropriate renovation method.
This add-on may also be used in conjunction with other additional survey technologies such as Sonar surveying.